The first instruments had 20 buttons, arranged in
two rows per side, with the rows playing in keys a fifth apart.

Though the 2-row instruments are still made, the "Anglo," as it came to be called, underwent development similar to that which
occured with German concertinas. The two "home" keys remain, but larger
instruments are capable of a full chromatic
scale on both press and draw in the right hand. Aside from the central
row however, the layout is quite different from the German concertinas.